31 January 2009

Issue No. 17 of Tentacle, the annual newsletter of the IUCN/Species Survival Commission, Mollusc Specialist Group, edited by Rob Cowie of the University of Hawaii, is now available here, where all the previous issues can also be accessed.

This is the 3rd Tentacle issue in which I have an essay that was based on a post that first appeared on this blog. My piece titled "Will assisted colonization be a viable option to save terrestrial gastropods threatened by climate change?" is on p. 14. It is a much revised version of this post.

I decided to turn that post into an essay for the Tentacle when in early November of last year I received an e-mail from a reader who was inquiring if I would object to having my blog post cited in a manuscript in preparation.

The value of blogging in providing an outlet to test the edibility of half-baked ideas has become very clear to me now.

Posts about the previous issues of the Tentacle in which I had pieces inspired by earlier blog posts are here and here.

There are many other good articles in Tentacle #17. Download a copy now.

30 January 2009

Here is another installment in what is turning into a series of posts on slug development and anatomy.

Last night I dissected a specimen of Arion subfuscus, a European slug that has long been naturalized in the U.S. I cut the mantle along 3 of its edges and turned it inside out. Here is what the inside of the mantle looks like. The top border would be along the right side of a live slug.

What is not visible in my photograph is the ureter that runs from the kidney alongside the rectum to the penumostome, the breathing hole. Interestingly, the kidney of Arion is shaped like a donut with the heart sitting in the hole in the middle. The membrane to the front of the kidney is the lung. It is vascularized, but the veins are not visible in my picture. The opening of the rectum, like that of the ureter, is within the penumostome.

Next, I separated the kidney from the mantle to which it was loosely attached and pushed it aside. Underneath was a secret chamber full of shiny jewels, or more accurately, granules of calcium carbonate. Those constitute the "shell" of Arion.

Yesterday's post was about how during the development of another slug, Limax maximus, many pieces of calcium carbonate appear within the mantle and eventually fuse together to form the slug's shell. In Arion the individual pieces apparently remain loose and a one-piece shell never forms. We seem to be witnessing various evolutionary steps in the disappearance of shells as slugs descended from snails.

29 January 2009

I am trying to learn more about the internal, vestigial shells of some slugs. Surprisingly, very little research has been done with them and there seem to be only a handful of relevant papers. In situations like this, it is often best to start from the beginning. By coincidence, or perhaps not by coincidence, the oldest original scientific paper I own, George B. Simpson's "Anatomy and physiology of Polygyra albolabris and Limax maximus" published in 1901 in the Bulletin of the New York State Museum also happens to mention the formation of the internal shell of Limax maximus during the slug's embryonic development.

Simpson describes the development of Limax maximus starting from an egg:

The body of the animal as first observed consists of a slight swelling of the upper side of the cell mass...The swelling...very soon shows a tendency to divide into two parts (pl. 24, fig. 17), the anterior part of which is the foot proper, the posterior part the mantle, shell sac, etc. Even at this early stage the embryonic shell can be observed, consisting of a few dark colored crystalline plates, not yet united.

Here is pl. 24, fig. 17:

We skip ahead a bit:

The body now rapidly develops, as shown in figures 15 and 16, plate 25. The shell has also increased in size, consisting of numerous crystalline plates, not yet unified.

Here is pl. 25, fig. 16 (the arrow I added is pointing at the shell within the future mantle):

We continue:

As development proceeds a movement of the cells takes place from the ectodermal sac into the constantly enlarging body (pl. 26, fig. 1).

Here is pl. 26, fig. 1:

It still doesn't quite look like a slug. The yellow arrow is pointing at the mantle and the red one to the shell, which, although Simpson doesn't mention it, still consists of separate pieces.

Finally, after a little bit more development, the creature starts to resemble a slug.

The right tentacle is recognizable (blue arrow) and so is the pneumostome, the breathing hole (green arrow). The shell (red arrow) still has a granular appearance; the individual plates have not fully fused yet. Simpson doesn't mention when the pieces of the shell finally unify into one piece, but, presumably, this happens at around the time of hatching.

There are 2 important pieces of information we can gather from this account:

1. The shell starts to form very early during the development of the embryo within the mantle and there it remains in adults. It is truly a vestigial structure left over from the snail ancestors of Limax.

2. The shell does not start out as a tiny bit of crystalline substance that grows bigger and bigger; instead, it is formed from the union of many bits of crystalline plates. In adult Limax maximus, the shell is a flat, elongated plate (this post has a picture of the shell). Interestingly, in some other slug genera, for example, Arion, the shell remains as a mass of granules of calcium carbonate, which makes sense as the next stage in an evolutionary sequence.

28 January 2009

Dr. Liz Shea, Curator of Mollusks at the Delaware Museum of Natural History (DMNH) in Wilmington, Delaware, has announced that the 11th almost-annual meeting of the Mid-Atlantic Malacologists (MAM) will take place on Saturday 7 March 2009 at the DMNH.

From the announcement:

This one-day gathering is designed to facilitate contact among professional, amateur, and student malacologists who are interested in any aspect of molluscan biology. There are no dues, officers, abstracts, or publications. Meeting and parking are free of charge. Participants are encouraged to present and discuss data, compare notes on methods and problems, and catch up with colleagues and friends. Presentations (15 minutes max.) are very informal and cover topics as diverse as current research, trip reports, and collection issues.

It was a cold day; the temperature was hovering around freezing. All the small creeks running thru the park were frozen over.

Luckily I had a stable GPS signal and the coordinates measured in November also turned out to be quite accurate and so I didn't have any trouble locating the dead tree where the snails were. All of my 5 little yellow flags marking the exact locations of the buried snails were still standing.

However, I hadn't taken into account one possible complicating factor, that the soil would be frozen. It indeed was and although I could have dug into it—the snails were not very deep—I decided not to do anything forceful lest I broke the snails' shells during the operation.

According to Riddle (1981), Anguispira alternata avoids freezing of its tissues by undergoing supercooling almost down to -16 °C. Hopefully, my snails are doing the same where I left them in November. I will go back there during a warmer period.

The yellow signs posted all along the periphery of the park warned the visitors of "managed deer hunts". If they are hunting what lives in the park, that's not much of conservation, is it?

Obviously, the white-tailed deer (Odocoileus virginianus) is quite abundant around here. So, it wasn't too much of a surprise to run into some scattered deer bones soon after I entered the park.

I was excited when I also spotted the skull. Alas, its antlers had been chopped off, perhaps, by some bone-hungry scavengers. I decided it wasn't worth taking it home.

What was really surprising was to run into a 2nd skull a half an hour later. This one still had its antlers.

Just like the previous deer skull, this too had a strong sulfurous smell. Deer skin, bones, marrow or some other body part must have a high content of sulfur that gets released during decomposition. It is now soaking in a pan of hydrogen peroxide.

The left antler of this deer seems to have a malformation. Leave a comment if you can offer an explanation.

Did I say I had gone to the park to check up on snails? That will be the subject of tomorrow's post.

Thanks to a Nigerian friend of the family, who visits her home country every December, I have received another batch of giant African snail shells. This lot of 6 shells are even huger than the ones she had brought back last year. Last year I had identified them as Achatina achatina, but a reader subsequently indicated that they were actually Archachatina marginata. I'll stick with that name until further notice.

For weight measurements that do not require great accuracy, I use an old, battered Ohaus Cent-O-Gram triple-beam balance that I rescued from a certain one-way trip to a garbage dump several years ago during a laboratory clean-up. Most of these guys are only a few tenths of a gram below the balance's maximum capacity of 111 g.

This one was 109.65 g. In fact, one of them exceeds 111 g.

They are also longer than the standard 15-cm span of calipers. So, how do I measure them?

23 January 2009

A while ago I got curious about how much Carl Linnaeus had said about slugs in his Systema Naturae, published in 1758. Luckily, a digitized copy was readily available. Here is Linnaeus's description of the slug genus Limax from page 652 of volume 1.

Although I don't know Latin, I have been able to create a rough translation of these words with a little help from the various online Latin dictionaries and the one I pulled out of my vest pocket. What helped me most was, of course, Linnaeus's "telegraphic" style. Correct me where I am wrong.

The "flat disk" underneath is the internalized vestigial shell of the slugs in the genus Limax (also present in some other genera, for example, Deroceras). The hole on the right side that Linnaeus refers to was most likely the conspicuous pneumostome, the breathing hole. The openings of the rectum and the ureter are next to it, but the genital opening is closer to the front of the head and is normally kept closed except during mating. The picture below, originally from this post, is of a couple of mating Limax maximus. It clearly shows in the slug in the back the separate locations of the genital opening from which the penis is everted and the pneumostome, the large hole to the right of it.

If Linnaeus hadn't busied himself so much with the sex lives of plants and paid some attention to the livelier and certainly slimier sexual escapades of slugs, he certainly would have corrected his little mistake.

This picture from 1979 shows one of the old chemistry labs at our alma mater, the Boğaziçi University in Istanbul. The principal subject in the foreground is Teri Varnalı (whose name has appeared on this blog before), while yours truly is in the background behind an old (mid-1960s) Canon view-finder camera. The picture was taken by Ümit Yüksel, whose name has also been on this blog (here).

The contraption I had my camera attached to was a clampod, a makeshift monopod constructed from a laboratory ring stand (with a ring visible at its base) and a couple of clamps.

Apparently, I was attempting to photograph the lab benches cluttered with chemistry paraphernalia.

The label I had stuck on the slide has survived and the first 2 digits of the number indicate the year (i.e., 1979). The slide film I used was ORWO brand, made by a defunct East German manufacturer. We had to mail the exposed films to Germany to get them developed. The films would come back in rolls, which we would then cut into the individual exposures and slip those inside separately purchased plastic frames. The colors have help up suprisingly well.

19 January 2009

I spent most of yesterday afternoon cleaning and rearranging the basement. Three categories of objects account for ~80% of the occupied space: 1. papers and books; 2. specimens; 3. empty containers (miscellaneous plastic or cardboard boxes) for future specimens.

Among the specimens are probably more than 1000 containers of snail shells, about 200 vials of alcohol specimens and about 30 containers of litter and soil samples.

Most of the latter samples are from 2003 and 2006 when I was surveying the Monocacy Natural Resources Area and Belt Woods. Some of the litter samples have already been sieved, but not yet been sorted for snail shells. Others still need to be sieved first.

Each box or bag contains a little piece of card with the station code and the collection date written on it. It is best to keep that information inside the sample container, otherwise the two could get separated. And without that information a sample would be good only for the compost pile in the backyard.

There is no guarantee, however, that what's written on the card will be readable in the future, especially if the litter was slightly damp when the lid was closed.

Luckily in this case, the end of the card where the station code was written was in better shape than the rest and after I removed some of the overlaying filamentous stuff (fungal remains?), the station code appeared: MO-53 from the Monocacy survey. I can figure out the date from my field book.

A sample saved is a sample that needs to be processed. Maybe I should have dumped it into the compost pile right away.

18 January 2009

We start off with a wall painting in the veranda of a building. Note the cat on the left.

The next picture is a real graffiti. This was on a wall along a long yokuş from the Arnavutköy district by the Bosphorus to the hills behind. Note that it's in English.

The next picture is a trafo painting the purpose of which is to beautify the front of that oversized electrical box, which is a trafo (short for transformer). Trafos are quite common throughout the city and each seems to have a different painting of some old Istanbul scene.

Note the skull and bones sign on the left. No, that was not a pirate boat in the painting. The regular readers may recognize the sign as another one of those ölüm tehlikesi, or "risk of death" warnings that have appeared on this blog before (here and here).

16 January 2009

This issue contains articles on the mollusks found in excavations in Italy, United Arab Emirates and Israel, Papillifera bidens (=Papillifera papillaris) from Carthage and abstracts of recent relevant papers, announcements of upcoming meetings and other items of interest.

15 January 2009

Richard Thomas Lowe (1802-1874) was a British clergyman naturalist. He studied plants, fishes and snails, of course. I was at the Smithsonian's National Museum of Natural History in D.C. today and copied one of Lowe's papers on some of my favorite coastal snails, Melampus and Truncatella. The paper, titled "On the Genera Melampus, Pedipes and Truncatella: with Experiments tending to demonstrate the real nature of the Respiratory Organs in these Mollusca", came out in 1832 in the Zoological Journal.

Those were the formative years of malacology when even the broadest classifications of most of the mollusc species were debatable. Thus, in his paper Lowe was concerned with the question of whether Melampus and Truncatella were in the order Pectinibranchia or the Pulmonea. The former encompassed all the snails with gills, while the latter those with lungs. A simple dissection would have provided the answer, but "...the small size of the species, not to mention want of instruments and skill in the dissector" forced Lowe to resort to a series of experiments almost all of which involved the keeping of the subject snails in sea or fresh water or outside of water for various periods.

Not surprisingly, Lowe's experiments produced contradictory and puzzling results: both Melampus and Truncatella survived outside of water in wet containers, while when forced to remain in sea water they sometimes remained alive, sometimes died. At the end, however, he concluded that both genera were marine pectinibranchs.

Lowe didn't realize that the truth was a bit more complicated and, at the same time, much more interesting than his simple experiments could reveal. Truncatella breathes with a gill (see my dissection here), but lives its entire life on land near the sea, while Melampus breathes with a lung, lives at the edge of the sea, but enters it to reproduce via planktonic veliger larvae.

What we see in the case of Melampus and Truncatella is a mosaic-like pattern of mixed anatomies and lifestyles often observed during evolutionary transitions from one habitat to a drastically different one. The good ol' reverend was in for a surprise.

14 January 2009

Marla Coppolino sent this picture of an undescribed species of a snail-like creature with a blue shell next to her pet snails, probably a Neohelix albolabris (the bigger one) and a Mesodon thyroidus. She doesn't yet have a name for the creature, but we have already determined that it's in the family Knittedae, superfamily Craftoidea, class Woolapoda, a sister group of the Gastropoda. Marla indicates that once the new species is described, the specimen in the picture will be a yarnotype.

The next picture was from Richard Greene. It shows even a more bizarre creature: a human with the head of a snail. It's one of the drawings of the French artist J.J. Grandville from his book Les métamorphoses du jour first published in 1829.

Here is a closer look at Grandville's oddity. The bands on the shell and the black lip suggests Grandville had in mind Cepaea nemoralis when he drew his gastropodian servant.

13 January 2009

I am continuing with feeding trials of the 2 captive slugs, Megapallifera mutabilis. Here is one of them right after I interrupted its feeding on a piece of algae-covered beech.

The enlargement of the area in front of the slug's tail shows the teeth marks at the edge of the feeding track.

I still haven't figured out how exactly they create those marks, because I still haven't observed them feeding. As soon as I turn a light on, start opening lids and moving things around, the slugs stop feeding. The best I have done so far is the following shot. It shows the front of one slug's head. The mouth is right below the lower tentacles; it was, however, raised above the green crust of cyanobacteria.

12 January 2009

Via Abnormal Interests comes a link to a set of Google Earth placemarks for ~1300 Ancient Near East sites compiled by Olof Pedersén at the Uppsala University. The majority of the sites are from the Middle East and southeastern Turkey with a disappointingly few locations from the rest of Turkey.

From my own records, I will offer the coordinates of 10 archaeological sites in western Turkey that I’ve visited during snail surveys and are missing in the said compilation. The coordinates are the latitude followed by the longitude.

Kyme: 38.7594, 26.9358A city ~19 km northeast of Phokaia. At the given link it says “Kyme (Izmir)”, which is extremely confusing, because it sounds as if those were different names of the same place. In reality, Izmir (Smyrna) is 40 km to the southeast.

Notium: 37.9925, 27.1981Notium, also known as Notion, was a town located on a flat-topped cliff high above the Aegean Sea ~13.5 km northwest of Ephesus. It is perhaps best known by the naval battle that carries its name.

Claros: 38.0050, 27.1930A temple site only a little more than a kilometer north of Notium. This post has a picture I took at the site.

Ephesus (theater): 37.9410, 27.3422

Euromos: 37.3741, 27.6754This was another temple site south of Lake Bafa. Unfortunately, the Google Earth picture is of low resolution. The picture below is of the main ruins at the site of Euromos that I photographed in August 2000.

11 January 2009

I am suspecting that there has been a minor art movement behind the creation of signs for public restrooms in Turkey. However, so far it remains undeclared and rarely noticed. Nevertheless, as I noted in this post, the fruits of this creativity are not restricted to large cities but can be seen and enjoyed even in dinky towns off the beaten paths.

This sign outside the men's restroom was at a rest stop along the highway from Ankara to Istanbul last October.

One characteristic of this movement is that the men and women portrayed on the signs are almost always idealistic, unrealistic and old-fashioned characters. Probably no one looking like the man in this sign has ever entered this particular restroom. Would you say he has a late 19th century look about him? Perhaps they are expecting occasional time-travelers. More examples are in the previous post.

The favorable bias the Turkish artists must have towards smoking is also betrayed by their tendency to depict the male WC visitors with cigarettes and pipes in their mouths. A sizeable fraction of the Turkish population (males and females) smokes. But regulations restricting smoking in public places, especially in buses, for example, are being enacted. Hopefully, the future restroom signs will be a bit more contemporary and healthier looking.

09 January 2009

I had an aunt who had been born with a hearing deficit. Unfortunately, her handicap was not identified correctly when she was young; instead, she was thought to be mentally retarded, which she was not. She grew up to be self-sufficient and had a steady job for most of her adult life. Nevertheless, she lived alone in Istanbul and never had close friends. She loved cats. Cats gave her the affection and meaning that her interactions with humans couldn't provide.

The aunt did have a quirky personality. For one, she was a hoarder. Towards the end of her life, her apartment had become impassable. Once I visited the place just to take pictures (without her knowledge), which I still have. On another occasion, she requested my photographic services for a macabre and dismal project: I was to take pictures of her posing with a dead cat, her favorite who had died a few days earlier. I still have those negatives too.